1 /* 2 * linux/fs/ext4/fsync.c 3 * 4 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com) 5 * from 6 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr) 7 * Laboratoire MASI - Institut Blaise Pascal 8 * Universite Pierre et Marie Curie (Paris VI) 9 * from 10 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds 11 * 12 * ext4fs fsync primitive 13 * 14 * Big-endian to little-endian byte-swapping/bitmaps by 15 * David S. Miller (davem@caip.rutgers.edu), 1995 16 * 17 * Removed unnecessary code duplication for little endian machines 18 * and excessive __inline__s. 19 * Andi Kleen, 1997 20 * 21 * Major simplications and cleanup - we only need to do the metadata, because 22 * we can depend on generic_block_fdatasync() to sync the data blocks. 23 */ 24 25 #include <linux/time.h> 26 #include <linux/fs.h> 27 #include <linux/sched.h> 28 #include <linux/writeback.h> 29 #include <linux/jbd2.h> 30 #include <linux/blkdev.h> 31 32 #include "ext4.h" 33 #include "ext4_jbd2.h" 34 35 #include <trace/events/ext4.h> 36 37 /* 38 * If we're not journaling and this is a just-created file, we have to 39 * sync our parent directory (if it was freshly created) since 40 * otherwise it will only be written by writeback, leaving a huge 41 * window during which a crash may lose the file. This may apply for 42 * the parent directory's parent as well, and so on recursively, if 43 * they are also freshly created. 44 */ 45 static void ext4_sync_parent(struct inode *inode) 46 { 47 struct dentry *dentry = NULL; 48 49 while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 50 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 51 dentry = list_entry(inode->i_dentry.next, 52 struct dentry, d_alias); 53 if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode) 54 break; 55 inode = dentry->d_parent->d_inode; 56 sync_mapping_buffers(inode->i_mapping); 57 } 58 } 59 60 /* 61 * akpm: A new design for ext4_sync_file(). 62 * 63 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 64 * There cannot be a transaction open by this task. 65 * Another task could have dirtied this inode. Its data can be in any 66 * state in the journalling system. 67 * 68 * What we do is just kick off a commit and wait on it. This will snapshot the 69 * inode to disk. 70 * 71 * i_mutex lock is held when entering and exiting this function 72 */ 73 74 int ext4_sync_file(struct file *file, int datasync) 75 { 76 struct inode *inode = file->f_mapping->host; 77 struct ext4_inode_info *ei = EXT4_I(inode); 78 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 79 int ret; 80 tid_t commit_tid; 81 82 J_ASSERT(ext4_journal_current_handle() == NULL); 83 84 trace_ext4_sync_file(file, datasync); 85 86 if (inode->i_sb->s_flags & MS_RDONLY) 87 return 0; 88 89 ret = flush_completed_IO(inode); 90 if (ret < 0) 91 return ret; 92 93 if (!journal) { 94 ret = generic_file_fsync(file, datasync); 95 if (!ret && !list_empty(&inode->i_dentry)) 96 ext4_sync_parent(inode); 97 return ret; 98 } 99 100 /* 101 * data=writeback,ordered: 102 * The caller's filemap_fdatawrite()/wait will sync the data. 103 * Metadata is in the journal, we wait for proper transaction to 104 * commit here. 105 * 106 * data=journal: 107 * filemap_fdatawrite won't do anything (the buffers are clean). 108 * ext4_force_commit will write the file data into the journal and 109 * will wait on that. 110 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 111 * (they were dirtied by commit). But that's OK - the blocks are 112 * safe in-journal, which is all fsync() needs to ensure. 113 */ 114 if (ext4_should_journal_data(inode)) 115 return ext4_force_commit(inode->i_sb); 116 117 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 118 if (jbd2_log_start_commit(journal, commit_tid)) { 119 /* 120 * When the journal is on a different device than the 121 * fs data disk, we need to issue the barrier in 122 * writeback mode. (In ordered mode, the jbd2 layer 123 * will take care of issuing the barrier. In 124 * data=journal, all of the data blocks are written to 125 * the journal device.) 126 */ 127 if (ext4_should_writeback_data(inode) && 128 (journal->j_fs_dev != journal->j_dev) && 129 (journal->j_flags & JBD2_BARRIER)) 130 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, 131 NULL, BLKDEV_IFL_WAIT); 132 ret = jbd2_log_wait_commit(journal, commit_tid); 133 } else if (journal->j_flags & JBD2_BARRIER) 134 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL, 135 BLKDEV_IFL_WAIT); 136 return ret; 137 } 138